The present invention generally relates to rotary recording medium reproducing apparatuses, and more particularly to a rotary recording medium reproducing apparatus capable of protecting a reproducing stylus in an operational state, by setting the electrical potential of a rotary recording medium to the same electrical potential as an electrode of the reproducing stylus, so that a discharge current which damages the electrode of the reproducing stylus substantially does not flow.
Apparatuses have been realized for reproducing a recorded information signal according to variations in electrostatic capacitance between an electrode of a reproducing stylus and a rotary recording medium (hereinafter simply referred to as a disc) in which an information signal such as a video signal and an audio signal is recorded as variations in geometrical configuration. Upon reproduction, the reproducing stylus made of diamond makes contact with the surface of the disc which is made of a synthetic resin and rotating at a high rotational speed, to relatively scan the disc. Accordingly, electrical charges of opposite polarities are generated and accumulated at the reproducing stylus and the disc due to electrostatic induction, and a polarity difference is introduced between the reproducing stylus and the disc. Moreover, since the disc is handled when accommodated within a jacket made of a synthetic resin, the disc is in an electrified state due to the static electricity. Hence, in some cases, a potential difference already exists between the disc and the reproducing stylus at the point when the disc is loaded into the reproducing apparatus. When the potential difference between the reproducing stylus and the disc becomes large, a discharge current flows between the reproducing stylus and the disc. In this case, the electrode of the reproducing stylus is destroyed by the above discharge current, and it instantly becomes impossible for the reproducing stylus to perform reproduction.
Conventionally, in order to protect the reproducing stylus, a capacitor was provided in a path of the reproduced signal, to electrically insulate the electrode of the reproducing stylus with respect to a reference potential point on the side of the disc for direct-current. By use of this construction, the discharge current does not flow between the electrode of the reproducing stylus and the disc. The above capacitor operating to restrict the discharge current is limited to a capacitor having a low voltage rating, due to the location where the capacitor must be provided. However, in some cases, the potential difference between the disc and the reproducing stylus exceeds the above voltage rating of the capacitor. In this case, the capacitor is destroyed and the discharge current flows through the electrode of the reproducing stylus, to accordingly destroy the above electrode.